Field of the Invention
The present invention relates to an eyepiece lens and an observation apparatus having the same, and is suitable for observing an image displayed on an image display element in an electronic viewfinder used in, e.g., a video camera, still camera, or broadcasting camera.
Description of the Related Art
An electronic viewfinder used in an image pickup apparatus (camera) such as a video camera or still camera has conventionally used an eyepiece lens to enlarge and observe an image displayed on a liquid crystal image display. To easily view the image display surface in the electronic viewfinder, it is necessary to enlarge the image display surface such as a liquid crystal image display, or increase the observation magnification of the eyepiece lens.
However, a large image display surface upsizes the viewfinder. To downsize the overall viewfinder, the observation magnification of the eyepiece lens is preferably increased. To increase the observation magnification of the eyepiece lens, the positive refractive power of the eyepiece lens needs to be high. At this time, if the eyepiece lens is constituted by only lenses (positive lenses) with a positive refractive power, axial chromatic aberration and lateral chromatic aberration are greatly generated, and it becomes difficult to correct these aberrations.
To improve the performance at the time of observation, aberrations including chromatic aberration need to be corrected using a lens (negative lens) with a negative refractive power. An eyepiece lens constituted by three lenses including negative and positive lenses has conventionally been known.
Japanese Patent Application Laid-Open No. 2006-65265 has disclosed an eyepiece lens which is constituted by a positive lens, positive lens, and negative lens sequentially from the image display surface side to the observation side (eye point side), and has a long interval from the image display surface to the first lens. Japanese Patent Application Laid-Open No. 2011-221091 has disclosed an eyepiece lens which is constituted by a positive lens, negative lens, and positive lens sequentially from the image display surface side to the observation side, has a high enlargement ratio, and is compact in the entire system.